CMU Block Coverage Reference
| Block Type | Size (W×H×L) | Sq Ft / Block | Blocks / 100 Sq Ft |
|---|---|---|---|
| Standard CMU | 8″×8″×16″ | 0.89 | 113 |
| Half Block | 8″×8″×8″ | 0.44 | 225 |
| 4″ CMU | 4″×8″×16″ | 0.89 | 113 |
| 12″ CMU | 12″×8″×16″ | 0.89 | 113 |
| Standard Brick | 2¼″×3¾″×8″ | 0.13 | 785 |
Frequently Asked Questions
How many CMU blocks do I need per square foot?+
About 1.125 blocks per square foot for standard 8×8×16 CMU with 3/8" mortar joints. Multiply your wall area (length × height) by 1.125, then add 5–10% for waste. Round up to the nearest full block.
How much mortar do I need for concrete blocks?+
Rule of thumb: 3 bags of 80-lb mortar per 100 standard CMU blocks. A 200 sq ft wall using standard CMU needs about 225 blocks and 7 mortar bags. Always round up — running short mid-wall delays the pour.
What is the standard size of a concrete block?+
Standard CMU is 8"(H) × 8"(D) × 16"(L) nominal. Actual dimensions are 7⅝"×7⅝"×15⅝" — the 3/8" difference accounts for the mortar joint. Courses stack at 8 inches center-to-center vertically.
How much does a concrete block wall cost?+
CMU blocks run $2–4 each at most building supply stores. A 40-ft long, 4-ft tall wall (160 sq ft) needs about 180 blocks and 6 bags of mortar — roughly $400–800 in materials. Professional laying costs $8–20/sq ft in labor.